Interactions between Kluyveromyces marxianus from cheese origin and the intestinal symbiont Bacteroides thetaiotaomicron: Impressive antioxidative effects

The effects of yeast Kluyveromyces marxianus S-2-05, of cheese origin, were assessed on the intestine anaerobe symbiont Bacteroides thetaiotaomicron ATCC 29741 to unveil any changes in its antioxidant properties. To this end, these microorganisms were grown and incubated either separately, or co-incubated, under anaerobic atmosphere. Afterwards, the microbial cells were recovered and washed, and extracts were prepared using a sterile detergent solution to mimic the intestine detergent content. The extracts prepared from K. marxianus S-2-05 and reference strain K. marxianus MUCL 29917, grown under different conditions, were assessed for their antioxidant properties against superoxide anion and hydrogen peroxide. Extracts from both yeasts showed antioxidative effects, which were particularly important for K. marxianus S-02-5 after anaerobic incubation. Moreover, K. marxianus S-02-5 displayed a high level of activity against the aforementioned reactive oxygen species, enhancing that of B. thetaiotaomicron ATCC 29741, after the co-incubation process. Two-dimensional polyacrylamide gel electrophoresis was used to separate the proteins extracted. Superoxide dismutase, thiol peroxidase, rubrerythrin -intensively produced by B. thetaiotaomicron induced by the yeast-were identified by mass spectrometry. The antioxidative potential evidenced for K. marxianus S-02-5 is another advantage which could justify the utilization of this strain as a probiotic for countering intestinal inflammatory processes. © 2017 Elsevier Lt

Fungal diversity of “Tomme d'Orchies” cheese during the ripening process as revealed by a metagenomic study

Tomme d'Orchies is an artisanal pressed and uncooked cheese produced and marketed in the north of France. This study aimed at showing the fungal microbiota evolution of this cheese using a metagenetic based Illumina technology targeting the ITS2 domain of 5.8S fungal rDNAs. To this end, samples were taken from the rind and the core of different cheeses, after 0, 1, 3, 7, 14 and 21 days of ripening. The data underpinned the prevalence of Yarrowia lipolytica and Galactomyces geotrichum for both microbiotas. Unusual species including Clavispora lusitaniae, Kazachstania unispora and Cladosporium cladosporioides were also detected, but their origins remain to be ascertained. The metagenomic revealed also the presence of Kluyveromyces and Debaryomyces species. © 2017 Elsevier B.V